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Sharing some personal insight on avoiding a potential hazard

Discussion in 'Pro/Adv Discussion' started by CCDD, May 12, 2016.

  1. CCDD

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    Prior to purchasing my first P3P back in November, I spent countless hours on this forum both reading and absorbing as much information as possible before ever attempting to fly my Phantom. To date, I've logged over 150 successful flights totaling nearly 450 miles. Aside from one component failure resulting in my P3P ending up in a lake, all else has gone off without a hitch. Recently, I purchased an Inspire 1 Pro which is truly an amazing bird however, my P3P is still my "go to" bird to quickly grab and get airborne without much fuss.
    DJI handled my warranty claim on my lost P3P and the replacement was received this past Tuesday.
    After going through FW updates, IMU and compass calibrations, assuring all parameters were correctly set up in DJI GO app and of course running though preflight check of things, all appeared in order and normal. Upon take off and attempting to hover a 4-6 ft, the P3P starting going left without any stick input from me. I immediately took control back and struggled to bring her back down. I completed another compass calibration, checked all settings again and attempted to take off again. This time, it headed straight back at me, I was tempted to bat it down with my "monstrous" paws however, I chose to swiftly move out of the way and abruptly landed it. I did notice a compass error during this most recent flight and was able to repeat this warning without even taking off. These events were a reminder that no one other than the one piloting should be standing any where near the take off point. Had this taken place where I often fly, there would've likely been 1/2 dozen people watching, although not too close, it could've resulted in a very dangerous situation with what appears to be an erratic compass issue. I've since taken it to an open field, far from any possible interference, calibrated and again, the same error appeared. I'm not going to upload any flight logs as it's obvious there's a serious problem right out of the gate on this one.


    I contaced DJI and explained this was the replacement they sent me and was told they would forward an overnight shipping label and would have it repaired and back in my hands within 5 days. Although I want a replacement rather than a repair, they wouldn't budge. Thankful for two things, no one got hurt and I have the Inspire 1 at home just itching for me to fly her.
     
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  2. ianwood

    ianwood Taco Wrangler
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  3. Morgas Resnak

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    Call me silly but, I calibrate on every single flight and always use a checklist. Guess the best defense is common sense, and good points. Thanks for the insight too.
     
  4. CCDD

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  5. robinb

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    I wonder if it is something in this location that is upsetting the compass. ?

    Any reinforced concrete or metal pipes underground.?
     
  6. MikeyOnline

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    This is one reason I don't calibrate my compass every flight! With each calibration, you risk interference or some issue in the local area causing a bad calibration. So me: when I get a good one that has proven itself, I stick with it until I move (signifiantly) to a different location. That said, I've seen plenty of CCDD's posts and know he's not going to fall into any of the compass calibration potholes so I feel like this one is definitely a bad compass.

    On that subject, I've never understood why a compass calibration error should cause the AC to just fly off. Unless the GPS is broken too, the FW should be sophisticated enough to make it hover in one spot after some minor initial movement. Sure, it doesn't know which way it's turned but if there's no control input and it sees that it's moving south quickly, start changing the motor biases until it slows down/comes to a stop. Can't be that hard.

    Mike
     
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  7. coopdog

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    I had an odd, somewhat similar occurrence with my P3A. I took it to a more urban location than I usually fly but not anywhere near an airport. I did all my normal pre-flight routine. Nothing was out of the ordinary. The second I went airborne the bird went hard left and I had to crash it. Thankfully it didn't do any damage since it was only a foot or so off the ground. I calibrated to compass. Same result. What the heck? I thought.

    I pull up the map and sure enough I was very near, but not in, a no fly zone as a result of my proximity to an NFL stadium. Again, if you go by the map, I was clearly out of the circle. Nevertheless, I walk around to the other side of a building and further away from the circle and it flies just fine.

    So I fly it toward the imaginary boundary, its stops moving forward. It only goes right or left when I add forward input on the control stick.

    My two observations: 1. The rotors started in, or very near, a no fly zone but it wanted out the second it went airborne. 2. If flying, it will not just stop forward movement at a boundary, it will actually fly left or right when given forward input on the stick.There is something about being on that fringe that made it behave unexpectedly.
     
  8. Reed L

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    Just for kicks, you could turn on vps, drop it into atti and see if it holds any better :)
     
  9. Erroll

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    Silly.

    Really.


    There is little to no benefit from calibrating before every flight. There is however an element of risk in doing so.
     
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  10. Morgas Resnak

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    Like I said, call me silly, but the best defense is common sense and to each his own.
     
  11. Not A Speck Of Cereal

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    I've had my UAV react crazy like that on maybe 2, 3 occasions and it ALWAYS ended up being an issue with the flying location, magnetic or heavy radio interference.
     
  12. HueJorgan

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    I calibrate every time I start flying in a new location never had any problems

    App says calibrate every time so I do
     
  13. tcope

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    The app reports errors only. So you get an error every single time?

    The manual states some _like_ this. That does not mean if you pick it up and set it down 5' away that you need to recalibrate. You need to understand _why_ calibration make a difference in order to understand what DJI means by new locations. It has to do with magnetic north... which does not change over 1, 2, 5, 10 or 20 miles.
     
  14. tcope

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    I'd recommend trying an IMU calibration before sending it in. perhaps the level is off. You can also check this within the app... but I'd do a new one anyway.
     
  15. Not A Speck Of Cereal

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    Just to be clear: When you first fly for the day and bring up the general settings and see the big Calibrate button, that doesn't mean that it is telling you to Calibrate -- it's just the button you push if you need to calibrate.

    As tcope said, you don't need to calibrate unless you have an error. Additionally, you should calibrate when you do not have an error, but have traveled a relatively long distance from where you last calibrated.
     
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